US 2457002 A
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Description (OCR text may contain errors)
Dec. 21, 1948. 4 a, a. sP|Ro xflsuuwma 'aousme F013sum-1111mm, APPARATUS Filed Doc. 30, 1944 Inventor:
Benjamin E. Spiro,
Patented Dec. 21, 1948 INSULATING HOUSING FOR ELECTRICAL APPARATUS Benjamin E. Spiro Philadelphia, Pa., assignor to General Electric Company, a corporation of New York Application December 20, 1944, Serial No. 568,984
4 Claims. 1
My invention relates to insulating housings for electrical apparatus such as electric circuit breakers and more particularly for electric air circuit breakers of the type disclosed and claimed in Linde Patent 2,293,513, granted August 18, 1942, and assigned to the same assignee as the present application. Specifically my invention is an improvement on Boehne Patent 2,293,452, granted August 18, 1942, and also assigned to the same assignee as the present application.
As is disclosed and claimed in the above mentioned Boehne patent, air circuit breakers of the type disclosed in the above mentioned Linde patent produce large amounts of highly heated arc gases in the short interval of time during the circuit interrupting operation. The explosive-like generation of incandescent gases by the circuit breaker during the interrupting operation may cause serious injury and damage to adjacent operators and equipment unless the gases are sumciently cooled to an insulating state before being vented from the arc chute or breaker housing. The cooling of these gases introduces another problem, i. e., possible reduction of are interrupting capacity due to excessive back pressure particularly where a compact design is required. In accordance with the above mentioned Boehne patent the arc chutes of the circuit breaker are enclosed by a box-barrier arrangement of insulating material which deflects and renders harmless the arc and switching gases blown from the are chutes of the circuit breaker while maintaining a high interrupting capacity of the circuit breaker and a high insulation level of the complete equipment. The box-barrier construction used heretofore comprised a plurality of sheetlike members or panels of insulating material which were arranged in the form of a box and which might be divided by. a plurality of barriers to isolate thevarious arc chutes of the circuit breaker. These box-barriers were usually fastened together by a plurality of screws or Other metal fastening means.
It would be desirable to provide a boxbarrier which does not employ any metal iastenings of any kind which has a greatly increased electrical creepage path which is more effective from the standpoint of gasproofness, which has a more pleasing finished appearance, and furthermore which is less expensive to manufacture.
It is an object of my invention to provide an insulating housing or box-barrier for gas producing electrical apparatus such as electric air circuit breakers which has the advantages enumerated above.
It is another object of my invention to provide a new and improved insulating housing for the arc chutes of electric circuit breakers.
Further objects and advantages 0! my invention will become apparent as the following description proceeds and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.
For a better understanding of my invention reference may be had to the accompanying drawing in which Fig. 1 is an elevational view, partly in section, of an electric circuit breaker embodying my invention; Fig. 2 is an end view, partly in section, of Fig. 1; Fig. 3 is an enlarged perspective view of a portion of the insulating housing of Figs. 1 and 2; Fig. 4 is an end view of a portion of Fig. 3 prior to assembly as in Fig. 3; Fig.'5 is a perspective view of a portion of Fig. 3 illustrating one step in the assembly; Fig. 6 is a sectional view taken on line 6-4 of Fig. 3, and Fig. '7 is an enlarged, exploded view of a portion of Fig. 3.
Referring now to the drawing, there is illustrated an electric circuit breaker substantially identical with the electric circuit breaker disclosed and claimed in copending application Serial No. 568,983, Spiro et al., filed concurrently with the present application and assigned to the same assignee as the present application which has matured into Patent 2,445,190, granted July 13, 1948. The electric circuit breaker illustrated comprises a main supporting frame I, for the movable contact structure which comprises a relatively fixed contact 2 and a movable contact 3 which is pivotally mounted at 4 on one end of the circuit breaker conductor stud 5. The stationary contact 2 is electrically connected to a conductor stud 6. Pivotally mounted contact 3 is operated by means of an operating rod I connected to an actuating mechanism (not shown) preferably carried by the frame I. The conductor studs 5 and 6 serve as plug type disconnect contacts for the circuit breaker unit and when they are connected to alive power circuit relative separation of the contacts of the circuit breaker will cause an arc to be drawn.
For the purpose of interrupting this power arc an arc extinguishing structure generally indicated at 8 is mounted in the frame i so asto receive the arc. Suitable means, such as magnetic blow-out coils are provided to force the arc into the arc chute. Generally such a circuit breaker comprises a plurality of arc chutes, one for each phase conductor of the power circuit to be controlled. As illustrated in Fig. 2 of the drawing, three are chutes are shown each connected to a different set of conductor studs to control the conventional three-phase electric circuit. As illustrated in the drawings the arc chutes I are oi the so-called down-draft type such as is disclosed in Linde Patent 2,335,068, granted November 23, 1943, and assigned to the same assignee as the present application. By downdraft type is meant that the arc gases from the arc chute are discharged downwardly. It will be understood, however, that my invention is equally applicable to circuit breakers such as are shown in the above mentioned Boehne patent where the arc gases from the arc chute are discharged laterally rather than downwardly.
The circuit breaker thus far described would probably in the case of severe overloads or short circuits eject incandescent gases in varying amounts. This obviously cannot be tolerated in an indoor station where such breakers are usually employed, as attendants might be seriously burned and also damage to other equipment might result in the case of flashover due to the heated gases within the breaker'enclosure which is usually a metal enclosure. In order more completely to house the interrupting device and guard against injuries or fiashover due to possible ejection oi hot gases, there is provided an insulating housing or box-barrier 9. This housing comprises a front wall or panel ill, a top wall or panel il, a bottom wall or panel I 2, side plates or panels I: and I4, and a plurality of partitions or interphase barriers l5. These panels are really sheet-like members formed of insulating material and joined together as a unitary structure in the form of a box-like housing which is inserted into the position indicated in Figs. 1 and 2 and supported by any suitable means, such for example as the lugs IS in Fig. 2
extending from the frame I.
In accordance with the disclosure of the above mentioned Boehne patent, the box-barrier 9 receives the gases discharged from the arc chute 8 and permits these gases to escape to atmosphere through a plurality of openings such as H in the bottom wall I! and a plurality of openings such as l8 in the front wall 10. By the time these gases are exhausted to atmosphere through openings l1 and I8 they are sufliciently cooled and by virtue of the box-barrier 9 flashover is prevented since the arc chutes 8 are isolated from each other and the arc gases are prevented from impinging against the metallic frame of the circuit breaker until they are sufliciently cooled.
Heretofore the box-barriers such as 9 comprised a plurality of insulating plates fastened together by suitable metal screws or rivets. The metal screws or rivets greatly increase the probability of flashover and furthermore the construction was not gas proof at the Joints which tended to increase the possibility of fiashover.
In accordance with my invention the boxbarrier is constructed with substantially no metal parts at all and furthermore the joints are substantially gas proof and provide a very long creepage path. In addition a much more pleasing construction is presented which is much less expensive to manufacture.
In accordance with my invention I provide a Junction strip or insulating member for Joining two adjacent sheet-like members at a predetermined angle, which is preferably a right angle. This junction strip or molding is generally indicated in the drawings as I! and comprises a strip of insulating material which is produced by extruding through a special die of the desired configuration, a suitable plastic material. I have found that plastic material such as cellulose esters and particularly aceto-butyrate is a very desirable extrudable material from which to form the strips or moldings IQ for in addition to being insulating, these materials are tough, hard and resilient and which properties account for the effectiveness of the corner jointing members for the insulating housing of my invention. The strips is are produced in the particular crosssectional configuration clearly indicated in Fig. 4 comprising a pair of outer angularly disposed flanges 20 arranged somewhat less than right angles with each other, and an inner L-sectioned member 2| intermediate the flanges 20 and integral with said flanges so as to define a pair of longitudinal grooves or recesses 22 for receiving edges of the sheet-lie members or panels such as H), II, l2, l3 and Id. The strips or moldings l9 when initially extruded as shown in Fig. 4, also have the outer flanges 2D curved somewhat in arcuate form. The material is resilient, as already stated, so that when two adjacent sheet-like members are assembled in the associated recesses 22 the curvature will disappear for the flanges 20 will press sealingly upon the panel surfaces so as to lie substantially flat thereon as is shown in Figs. 3 and 6 when the panels are opened to their full predetermined degree relationship one with the other.
In order to lock the insulating member I! to the sheet-like members or panels such as III, II, l2, l3 and I4, each of the sheet-like members or panels is provided with a shallow, longitudinally extending groove 23,near to the edge of the panel and parallel to said edge. The outwardly extending edges of the flanges 20 of molding l8 preferably terminate in a longitudinally extending tongue 24 which is adapted to fit into a cooperating groove 23 of an associated panel thereby effectively providing means for holding the strip [9 securely to the sheet-like member or panel. Because the molding i9 is hard and tough, it serves adequately as the means for effectively joining together two adjacent panels disposed at a predetermined angle with respect to each other. It will be obvious that with this arrangement any two adjacent panels may be prearranged. at said predetermined angle with each other after which a joining strip I9 can then he slid endwise into place between them with the tongues 24 fitting nicely into the grooves 23. I have found, however, that by making the insulating strip 19 from resilient material, a sheet-like member or panel may be sprung directly into the molding, as is clearly shown in Fig. 5 where the sheet-like member [2 is depicted in the process of being entered laterally into the insulating strip [9 which latter is already assembled in place on the panel In. Conversely, the length of joining strip or molding is may be sprung directly onto the edge of a panel in preterence to sliding it lengthwise into position on the grooved panels, if desired.
It will be understood from the above description that the four molding or insulating members joining panels l0 and 13, I0 and l4, l0 and I2, and I0 and II can not slide longitudinally out of position once the box-barrier is assembled for these four members I9 which form a rectangular frame around the front panel iii, are in abutting engagement with one another at each 01' their ends where they have been cut so as to form mitered corner joints as clearly illustrated not extend outside the box barrier.
8 toward the bottom of Figure 2. It is possible, however, for the four side moldings or insulating strips 18 which join the panels II and I3, II and I4, I! and ii, and i2 and ll to slide longitudinally out of position when employing the I tongue and groove method described above for only one end of each of these four side moldings is in abutting engagement at one of the aforementioned mitered corner Joints. To prevent these last four moldings or insulating members from creeping away so as to open up these mitered comer joints of the box-barrier, I provide additional means for keying these particular moldings into position which is best illustrated by Figs. 3 and 6. A small drilled hole 25 is provided in the panel such as I! between the groove 23 and the edge of the panel. The molding or insulating member I! is then permanently deformed by means of a hand punching tool in a manner indicated at 26 in Fig. 6, so that the extension which projects into the hole or opening 25 prevents any relative sliding movement between the molding i9 and the panels such as M and I3.
The interphase barriers l5 are supported in grooves such as 21 provided in the panels III, II, and ii. In order to lock each of these barriers in position in grooves 21 a single slotted dowel pin 28 best shown in Figs. 3 and 7 may be provided. This dowel pin has a portion of reduced cross section 29 adapted to be inserted in a cooperating opening 30 formed in bottom plate i2, as is clearly shown in Fig. 7. The slot in the dowel pin 28 cooperates with a notch 3| cut into the interphase barrier 15. This dowel pin may be made of metal if desired since it does Preferably, however, this dowel pin is also formed oi insulating material.
In order to assemble the box-barrier 9 the bottom and front panels l2 and I0, respectively, could first be joined together by sliding or springing the molding l9 between them into position. Next the side plate I3 could be put into position while the vertical molding l9 between panels ill and i3 is slid into position. The two interphase barriers ii are then positioned with their lower and side edges in grooves 21 and with the locking, dowel pins 23 in place as depicted in Figure 3. The top panel II can then be placed into position so that its grooves corresponding to 21 in i2 engage the upper edges of interphase barriers IS. The upper horizontal molding i9 between panels ill and Il may then he slid into position from the end to which panel 14 is to be connected. The vertical molding l9 between panels l0 and i4 must then be sprung onto front panel i0 after which panel H is then sprung into position into this molding. At this stage of the assembly, all panels and barriers of the box-barrier 9 are properly in place, interlockingly keyed therein by the inturned flanges 24 of the four moldings is which latter now completely enframe the front panel Iii. It will be evident that these four moldings constituting the frame around the panel ID are themselves interlocked effectively and permanently together for they are incapable 01' any end movement due to their abutting relationship at the mltered corner joints. The remaining four side moldings which are horizontally disposed and which join the panels II and i3, i2 and l3, l2 and II, and ii and I4 now can he slid lengthwise into position, whereupon the live panels l0, Ii, l2, l3 and I4, the two interphase barriers it and eight moldings II are all interlocked into a rigid, com
pletely insulated box-like gas prooi struc e. To prevent relative movement between the ast four horizontal moldings II which were assembled in the box-barrier 8, these moldings may be deformed by a hand-punching tool so that the depression 26 formed thereby engages with cooperating openings 25 in the panels I! and I4.
From the above discussion it will be obvious that I have provided a box-barrier construction containing no metal members whatever, which includes a very long creepage path at the joints for minimizing voltage breakdown theretrhough, which has a very pleasing appearance and which is simpler and less expensive to manufacture than constructions used heretofore. Moreover, the Joints. are substantially gas proof for the resilient flanges 20 press effectively in weatherstrlp fashion upon the surface of the panels due to the flange curvature and because I have made the included angle between these flanges less than that between the associated adjacent panels.
While I have shown and, described a particular embodiment of my invention, it will be obvious to those skilled in the art that various changes and modifications may be made without departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.
What I claim as new and desire to secure by Letters Patent of the United States is:
1. An insulating housing for protecting electrical apparatus, said housing including a plurality'of insulating side panels maintained juxtaposed in predetermined angular relationship, means for conjoining together certain adjacent edges of said panels comprising a junction strip of resilient insulating'material which integrally includes a pair of outer flanges angularly disposed relative to one another and an inner L- sectioned member spaced therefrom to define therebetween a pair of longitudinal recesses in said strip into which said certain adjacent panel edges are received, the included angle between the flanges of said flexible strip when free of said panels being less than that maintained be tween said adjacent panels so that said flanges press eifectively upon the panel surfaces to form a gas seal thereat, and means for locking said certain panel edges in said recesses including cooperatingly matching projections and indentations for said panel edges and said junction strip.
2. An insulating housing for protecting electrical apparatus, said housing including a plurality of insulating side panels maintained juxtaposed in predetermined angular relationship, means for conjoining together certain adjacent edges of said panels comprising a junction strip of resilient insulating material which integrally includes a pair of outer flanges angularly disposed relative to one another and an inner L- sectioned member spaced therefrom to deflne therebetween a pair of longitudinal recesses in said strip into which said certain adjacent panel edges are received, the included angle between the flanges of said flexible strip when free of said panels being less than that'maintained between said adjacent panels so that said flanges press effectively upon the panel surfaces to form a gas seal thereat,'and means for locking said certain panel edges in said recesses comprising a projecting longitudinal tongue integral with each said flange and a corresponding groove cooperating therewith in each said certain panel edge.
3. An insulating housing for protecting electrical apparatus, said housing including a plurality of insulating side panels maintained juxtaeffectively upon the panel surfaces to form a gas seal thereat, and means for locking said certain panel edges in said recesses comprising a projecting longitudinal tongue integral with each said flange and a corresponding groove cooperating therewith in each said certain panel edge, the said cooperating tongues and grooves constituting the sole fastening means for preventing separation between said certain panel edges and said junction strip.
4. An insulating housing for protecting electrical apparatus, said housing including a first panel having a plurality of straight peripheral edges and an associated side panel maintained juxtaposed adjacent each said peripheral edge in predetermined angular relationship with said first panel, a plurality of junction strips for conjoining each said peripheral edge respectively to the edge of its associated side panel, each strip comprising a length of resilient insulating material which integrally includes a pair of outer flanges angularly disposed relative to one another and an inner L-sectioned member spaced therefrom to define therebetween a pair of Iongitudinal recesses in each said strip into which the associated juxtaposed panel edges are received, the included angle between the flanges of each said strip when free of said panels being less than that maintained between its associated side panel and said first panel, and means for preventing separation between each said strip and its associated panels comprising a projecting longitudinal tongue on each said outer flange and a cooperating groove near each associated panel edge, each end of each said Junetion strip being mitered and in abutting relationship to an end of its adjoining strip so that said plurality of strips completely enirame said first panel in interlocking relationship with said panels and with each other.
BENJAMIN E. SPIRO.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS Number Name Date 157,399 Holmes Dec. 1, 1874 728,688 Dyarmen May 19, 1903 906,208 Dewey et a1 Dec. 8, 1908 1,719,269 Kelle July 2, 1929 2,293,452 Boehne Aug. 18, 1942